Cephalopods are valuable marine molluscs that have become well- established research models in biomedicine, particularly in neurobiology and cell biology. Laboratory culture of squids and cuttlefishes has been refined recently, but high feeding costs (due to live diets) have been identified as the last major impediment to economical production. The unique feature of cephalopod nutrition that has been demonstrated in this grant is the nearly complete dependence on protein (i.e., amino acids) for (1) chemoattraction to foods, (2) energy metabolism and (3) growth. By comparison, carbohydrates and lipids play a minor role in energy metabolism. Furthermore, the rapid growth rates of cephalopods (3-10% body weight d-1) impose high demands on protein synthesis coincident with the demand for amino acid catabolism. This renewal is a request to conduct the final steps in formulating a nutritionally balanced diet for caphalopods. This entails quantification of the amino acid requirements of cephalopods, which will enable attainment of two major objectives: to formulate and evaluate a standard purified laboratory diet SPLD for basic science studies of nutrition, and to formulate and evaluate a practical moist pelleted diet (PMPD for the economical mass culture cephalopods. The PMPD would also become the vehicle for adding antibiotics to the diet. Specific Aims include (1) determining the essential amino acids needed by cephalopods, (2) determining the optimal balance of amino acids in a SPLD, (3) evaluating the attractability, palatability, and digestibility of the SPLD, (4) formulating a low-cost PMPD based upon the SPLD, (5) assessing the palatability of the PMPD and resultant animal growth, and (6) establishing cooperative programs to produce the SPLD and PMPD on a commercial scale. The accomplishment of these research aims represents the end-point for this research project, permitting commercialization of cephalopods.